Model Boat Mayhem
Technical, Techniques, Hints, and Tips => Batteries & Chargers => Topic started by: john44 on June 13, 2021, 02:17:15 pm
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Hi guys, is there a tester available that reads gel cell battery condition, I know component shop do one but that
Will only read the 12 v batteries. I am looking for 6v, 7 & 10 amp hrs batteries not 12 v
Any ideas?
John
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I am not a great Techy bloke, but I use a Multi Meter.
Len.
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Hi there, the late Dave M (bless him) advised one of these for me. Dave had one, and it does do the job. See what you think.
Digital Monitor LCD Watt Meter 60V/100A DC Ammeter RC Battery Power Amp Analyzer | eBay (https://www.ebay.co.uk/itm/223677371570?chn=ps&norover=1&mkevt=1&mkrid=710-134428-41853-0&mkcid=2&itemid=223677371570&targetid=1280824611338&device=c&mktype=pla&googleloc=9046771&poi=&campaignid=12125451065&mkgroupid=122721231597&rlsatarget=pla-1280824611338&abcId=9300480&merchantid=110529785&gclid=EAIaIQobChMI8JbJjvqU8QIVoRkGAB1yswDqEAQYBCABEgJrSfD_BwE)
John
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Hi Len,John, I have a multi meter and a watts up meter, but they don’t tell me what power a gel battery has left in it.
before or after charging. As I have said component shop do a digital 12 v reader but not a 6 v reader.
There are professional units that will read all gel types but you are looking at price off £250 plus.
John
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I think it is straightforward. A fully charged Gel cell battery would read a little in excess of 2.1v per cell so a nominal 6v battery with three cells would be just over 6.3v.
Colin
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What makes you think that a battery meter is accurate?
A watt meter will do the job when combined with a battery charge / voltage graph (which are also unreliable as they depend on so many variables) & a little experience of the battery. The bar display on voltage meters suggest a level of certainty that is very hard to believe.
A 6v lead acid battery is 3 x 2v cells & a 12v battery is 6 x 2v cells.
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What makes you think that a battery meter is accurate?
A watt meter will do the job when combined with a battery charge / voltage graph (which are also unreliable as they depend on so many variables) & a little experience of the battery. The bar display on voltage meters suggest a level of certainty that is very hard to believe.
A 6v lead acid battery is 3 x 2v cells & a 12v battery is 6 x 2v cells.
A watt meter can only tell you how much energy it "thinks" has gone into the battery. It doesn't "know" how well the battery has performed storing that energy. Equally, it doesn't know how efficiently the stored chemical energy will translate back into electric power. A good one might come close, but a lot of reliance is being placed in the accuracy of its voltmeter module.
Any battery that, from "flat", gets its full voltage too quickly is suspect. Its one of those Schrodinger type problems - after measuring you can say how much power WAS there, but by then it needs recharging, when you are left hoping that enough of what you put in will come out again.
As has been said elsewhere recently, each lead acid cell when charged should be 2.1 volts, multiply that by the number of cells. When cells droop to 2 volts, they need attention. As a rule of thumb, if the voltage comes up too quickly, the required attention is replacement.
In pre gel cell days, it was possible to get a definitive indication - you poked a hydrometer into the cell and read the Specific Gravity off. Only with liquid acid - gel wouldn't work and the things are sealed for life anyway.
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Hi guys thanks for your comments, I have a prolix multi checking device that checks NICD, NIMH,LIPO,LIFE but alas not
Gel cells
John
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That does not matter. Search "LED Rx Voltage Battery Checker 6.6~7.4V LiPoly/LiFe" (https://www.google.com/search?q=%22LED+Rx+Voltage+Battery+Checker+6.6~7.4V+LiPoly%2FLiFe%22) because it will do the job.
The same method has worked perfectly well on consumer items before sealed gel batteries were replaced by lithium batteries.
It was enough to indicate charge state on golf caddy cars or the ride on equivalent.
They are also excellent diagnostic indicators and as accurate as the on board voltage reference.
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Just checked a supplier "Less than two in stock" Doh! :-X
Regards Ian.
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Thanks for that H M S I. I HAVE 2 of those a Ripmax xtra and one with a voltage selector switch on it.
I will try them out and if I get good results I will fit them to plastic boxes.
Thanks to all that helped I think my problem is now solved.
John
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For lead acid cells (gel cells are just a different way of storing the acid) finding out the amount of charge left is very easy. After charging the battery should be left to sit for at least an hour then the voltage checked. At 100% charge the voltage will be 6.5V and the voltage will drop linearly with charge until at 6V it is 0% capacity. Intermediate capacities work out easily 6.4V is 80%, 6.3V is 60% etc. The same principal is used for 12V cells with 100% at 13V, 12.8V is 80%, 12.6V is 60% etc.
Jim
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Thanks Jim for some common sense and accurate numbers, I've been biting my tongue a bit with this topic. How many supposedly faulty models have we seen with a flat sla battery, just because it reads 6 ( or 12) volts.
Charles
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Yes chas I agree, that’s why I started the post because a 12 v or 6v reading tells you the
batteries need recharging so now hopefully everyone who reads these comments will come
out a lot wiser regarding gel batteries. :-)) :-)) :-))
John
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Yes chas I agree, that’s why I started the post because a 12 v or 6v reading tells you the
batteries need recharging so now hopefully everyone who reads these comments will come
out a lot wiser regarding gel batteries. :-)) :-)) :-))
John
John, can you clarify what you mean by condition in your opening post?
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Hi, in wanting to know the CONDITION of the battery means I would like to be able to read the energy in the battery’s
Before and after use.
John
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Any meter has to assume that the battery is in good condition, i.e. whatever the state of charge, it is a good one - if discharged it will take and hold a charge, if charged it can deliver. The meter can indicate the state of charge at the time, which is not quite the same as condition, which is the ability of the battery to do its job. A simple volt meter can tell you the voltage, which is one indicator. A recording amp meter can tell you how much current has gone into the sealed box. It can't tell you whether it is staying there or not.
A bucket lacking holes and having a good handle will be in good condition whether full or empty. I'm fairly sure, but probably about to be re-educated, that the meter that tells you a battery is leaking has yet to be put on the market.
OTOH, if a "smart" charger tells you that it can't bring the voltage up to where it should be, that is a firm indication that the battery is a dud. It might respond to a bit of brutal "dumb" charging, but for ever after should be regarded as "suspicious".
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Hi, in wanting to know the CONDITION of the battery means I would like to be able to read the energy in the battery’s
Before and after use.
John
Thank you. :-)) That's what I initially understood, then wondered, what the topic start was about.
Condition is a term sometimes used in the context of ageing and misuse.
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Thank you. :-)) That's what I initially understood, then wondered, what the topic start was about.
Condition is a term sometimes used in the context of ageing and misuse.
Yep that’s me ageing and misused {-) {-) {-)
John